A known autostereoscopic display device of the type of the previous paragraph is described in GB 2196166 A. This known device comprises a two dimensional emissive liquid crystal display panel having a row and column array of display pixels acting as an image forming means to produce a display. An array of elongate lenticular lenses extending parallel to one another overlies the display pixel array and acts as a view forming means. Outputs from the display pixels are projected through these lenticular lenses, which function to modify the directions of the outputs.
The lenticular lenses are provided as a sheet of elements, each of which comprises an elongate semi-cylindrical lens element. The lenticular lenses extend in the column direction of the display panel, with each lenticular lens overlying a respective group of two or more adjacent columns of display pixels.
In an arrangement in which, for example, each lenticular lens is associated with two columns of display pixels, the display pixels in each column provide a vertical slice of a respective two dimensional sub-image. The lenticular sheet projects these two slices, and corresponding slices from the display pixel columns associated with the other lenticular lenses, to the left and right eyes of a user positioned in front of the sheet, so that the user observes a single stereoscopic image.
In other arrangements, each lenticular lens is associated with a group of three or more adjacent display pixels in the row direction. Corresponding columns of display pixels in each group are arranged appropriately to provide a vertical slice from a respective two dimensional sub-image. As a user's head is moved from left to right a series of successive, different, stereoscopic views are observed creating, for example, a look-around impression.
The above described autostereoscopic display device produces a display having good levels of brightness. However, one problem associated with the device is that the views projected by the lenticular sheet are separated by dark zones caused by “imaging” of the non-emitting black matrix which typically defines the display pixel array. These dark zones are readily observed by a user as brightness non-uniformities in the form of dark vertical bands spaced across the display. The bands move across the display as the user moves from left to right and the pitch of the bands changes as the user moves towards or away from the display. Another problem is that the vertical lens results in a much greater reduction in resolution in the horizontal direction than in the vertical direction.
Both of these issues can be at least partly addressed by the well known technique of slanting the lenticular lenses at an acute angle relative to the column direction of the display pixel array. The use of slanted angles lenses is thus recognised as an essential feature to produce different views with near constant brightness, and a good RGB distribution behind the lenses.